In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
FIGS. 1 and 2 show two views of a class of rotary tools 1 that have a truncated body 2 to satisfy the operating conditions and environments for use with an automatic tool changer of a computer numerical control (CNC) machine. The body 2 has flattened or cut sides 4 to reduce the width of the tool 1. In addition to body alteration, this class of rotary tools may have an increased number of cutting inserts 6 located in radial progression on an edge 8 to compensate for missing inserts (due to the openings in the peripheral edges) as compared to the number of inserts arranged on the entire periphery of traditional round tools.
One of the popular applications of rotary tools such as those shown in FIGS. 1 and 2 is the machining of valve bodies of transmissions. Valve bodies consist of multiple channels to direct hydraulic fluid during transmission operations. FIG. 3 is an example of a valve body. One obstacle encountered during machining of valve bodies and similar parts with truncated rotary tools, as shown, for example, in FIGS. 1 and 2, is a very high level of noise generated by the rotary tool as it approaches the valve body. This noise can, in some instances, reach about 95 dB, which is in or close to a hazardous range and above the typical 85 dB threshold for wearing hearing protection.
In addition, it has been observed that a larger area of side walls of truncated rotary tools create much higher noise levels than traditional, completely round cutters of the same outer diameter. This noise level increases with increased speed of rotation (RPM). Also, the closer the bottom face of the truncated rotary tool is positioned relative to the face of valve body the higher lever of noise generated by the truncated rotary tool.
It would be advantageous to have a rotary tool that produces reduced noise levels at operating speeds. Advantageously, such reduced noise operation would only minimally sacrifice, preferably essential not sacrifice, machining speeds and parts throughput.